What is missing now is a guide of the build process. Writing one is a big task. Let's see if people is interested. I can answer here for now. About the build process I can say that I've built this bike with:

TIG welder

Angle grinder

Press drill

Car type hidraulic bottle jack (2 ton)

Lot of mild steel

Drill bits and cup saws

Printer+sticker sheets

Small hand tools

Few dollars for a lathe operator

3d printer (to build the welding jig)

A waterjet or CNC plasma cutter probably can accelerate the build by a big factor. I've cut the plates by angle grinder, and some are tricky.

As you can see, i've tried to design in a minimalist way to easy build and reduce weight. I think it is impossible to get rid of any part without taking some function. With my 720Wh battery, the bike is weighting 40Kg.

The design goes toward a trials bike (style that I enjoy). The seat is low, and that makes dismounting very easy. Probably a new seat mount can be done to make it more "enduro".

I love it!!!! I think the swing arm mounted motor makes a lot of sense. Of course a small increase in unsprung weight but you can't beat the simplicity. The use of all straight tubing is fantastic and the use of 3D printed parts to jig it up is genius. Also, in the picture, where the frame is jigged up, it looks like there are some white pieces that marked how cope the ends of the tubes. Are these 3D printed or flattened in CAD then printed on paper and then wrapped around the tube? The design and execution in my opinion are top notch and the finished product is a great looking bike! Well done!

I love it!!!! I think the swing arm mounted motor makes a lot of sense. Of course a small increase in unsprung weight but you can't beat the simplicity. The use of all straight tubing is fantastic and the use of 3D printed parts to jig it up is genius. Also, in the picture, where the frame is jigged up, it looks like there are some white pieces that marked how cope the ends of the tubes. Are these 3D printed or flattened in CAD then printed on paper and then wrapped around the tube? The design and execution in my opinion are top notch and the finished product is a great looking bike! Well done!

Thanks! I really appreciate your kind words. I've put a lot of nights (and days) on this project and sometimes I felt a bit alone

but I don't think a thread on motor sprocket will last very long under high motor power.. the rear sprocket needs to be bolted to the rear hub not threaded on with bicycle parts not designed for motor power.. the cost of a quality rear hub is not that much compared to the cost of a rear wheel rebuild/ redesign.. what is the cost of the battery, motor and controller; these are likely the higher cost components of an electric bike build..

Anyways, can't wait to see it completed and video in action.. best luck:)

but I don't think a thread on motor sprocket will last very long under high motor power.. the rear sprocket needs to be bolted to the rear hub not threaded on with bicycle parts not designed for motor power.. the cost of a quality rear hub is not that much compared to the cost of a rear wheel rebuild/ redesign.. what is the cost of the battery, motor and controller; these are likely the higher cost components of an electric bike build..

Anyways, can't wait to see it completed and video in action.. best luck:)

efMX

I agree with you that the threaded connection seems weak. But i've some data, for now, that looks promising:

Then, i've tried to unscrew the adapter from the steel hub and required enormous amount of leverage to do it. Suceeded and then screwed the adapter again and had a failure in 2 hours. Seems that the threads are deformed after the high torque and don't hold if deformed in the opposite way. So I learnt the lesson: never unscrew these parts.

Now i'm riding the aluminum hub used in OpenEMoto and is holding up. Time will tell.

What are the options? Oset sells hubs for 69 dollars, but the measures are not published. They don't seem to be thru axle type, and no information if they have sealed bearings or not (if they use sealed bearings it is trivial to convert to thru axle moto style)

The LMX hub looks good, but at 140 euro + shipping to Uruguay, it is a bit expensive for my budget.

but I don't think a thread on motor sprocket will last very long under high motor power.. the rear sprocket needs to be bolted to the rear hub not threaded on with bicycle parts not designed for motor power.. the cost of a quality rear hub is not that much compared to the cost of a rear wheel rebuild/ redesign.. what is the cost of the battery, motor and controller; these are likely the higher cost components of an electric bike build..

Anyways, can't wait to see it completed and video in action.. best luck:)

efMX

I agree with you that the threaded connection seems weak. But i've some data, for now, that looks promising:

Then, i've tried to unscrew the adapter from the steel hub and required enormous amount of leverage to do it. Suceeded and then screwed the adapter again and had a failure in 2 hours. Seems that the threads are deformed after the high torque and don't hold if deformed in the opposite way. So I learnt the lesson: never unscrew these parts.

Now i'm riding the aluminum hub used in OpenEMoto and is holding up. Time will tell.

What are the options? Oset sells hubs for 69 dollars, but the measures are not published. They don't seem to be thru axle type, and no information if they have sealed bearings or not (if they use sealed bearings it is trivial to convert to thru axle moto style)

The LMX hub looks good, but at 140 euro + shipping to Uruguay, it is a bit expensive for my budget.

The crash was big, but only impacts with the floor. Still my fork left bottle is bent in some way, and the stanchion can't slide. I feel that DH stuff is very expensive and not so strong. Should I go to pit bike forks? They are 1 1/8 compatible? recommended brands? Other ideas are welcome.

The crash was big, but only impacts with the floor. Still my fork left bottle is bent in some way, and the stanchion can't slide. I feel that DH stuff is very expensive and not so strong. Should I go to pit bike forks? They are 1 1/8 compatible? recommended brands? Other ideas are welcome.

sorry to hear about your crash and bike damage..

you may want to look into a DNM front suspension fork, more reasonable price and pretty beefy.. many people on here are using them for feedback from other riders.. another fork to consider would be the new RST, used on LMX and Sur ron.. most pitbike forks will not be compatible because they are shorter length designed for small diameter pibike wheels and would require modification to the bike head tube diameter or custom made headset steering bearing set.. also check into fast ace forks used on the Sur ron and early model zero electric motorcycles.. best luck, let us know how it turns out..

If you want cheaper than DNM pit bike fork but without air check out ''Volt'' (only metal springs in both legs), there are V1 and V2; v2 superior. There are even 770mm version which is even longer by few cm than most bicycle two crown forks. It does not have longer travel, only tubes are little bit longer. There are similarly good other pit bike forks for similar price range but I'm familiar with my mentioned ones specifically; check weight before buying as not all sellers specify as it does not matter so much for gas machines; I would say it's not worth if its heavier than 7kg for ebike;

But there is the reason why DNM pit bike fork costs three to four times than Volt pit bike fork. It is good fork.
The same good is FastAce pit bike fork; get whichever; both DNM and FastAce are very good.

Regarding bicycle DNM fork be aware that it is good fork but it lets inside dust and if you ride in dusty environment it will be affected sooner (needs service) than other some high end forks (which are more expensive). I don't know how it is actually relevant in real life... but experienced people are mentioning it.
I got DNM bicycle fork for 325eu shipped from CN.
You can get pit bike DNM for the same price if you really need that strength.

Be aware. Newest DNM bicycle fork has air in both legs, older version one leg has air only in one leg, other leg has metal spring; few hundred grams weight penalty; I prefer the older version.

I don't worry that bicycle fork will break with my style of riding. What I worry is bicycle brakes; rotors are too thin and overall bicycle brakes are flimsy unless it is very high end brakes and still they are not enough at speeds over 70km/h.

Off topic.
I heard one person made HTD M8 rear pulley out of composite material, 125 teeth. Can't ask him as he is Ukranian. If some who reads this are aware how it is done or have examples of those who have done it share it here plz or point where it is discussed.